A three-step laser stabilization scheme for excitation to Rydberg levels in 85Rb

We demonstrate a three-step laser stabilization scheme for excitation to nP and nF Rydberg states in ⁸⁵Rb, with all three lasers stabilized using active feedback to independent Rb vapor cells. The setup allows stabilization to the Rydberg states 36P_3/2–70P_3/2 and 33F_7/2–90F_7/2, with the only limiting factor being the available third step laser power. We study the scheme by monitoring the three laser frequencies simultaneously against a self-referenced optical frequency comb. The third step laser, locked to the Rydberg transition, displays an Allan deviation of 30 kHz over 1 second and <80 kHz over 1 hour. The scheme is very robust and affordable, and it would be ideal for carrying out a range of quantum information experiments.